Unipolar transverse flux machine

ABSTRACT

In a unipolar transverse flux machine, in particular a motor, having a rotor, which is comprised of two coaxial, ferromagnetic, toothed rotor rings, and a permanent magnet ring, which is magnetized in an axially unipolar fashion and is clamped axially between these rotor rings, and having a stator, which is concentric to the rotor shaft and has U-shaped stator yokes that represent the magnet poles, yoke elements, and a stator winding, in order to achieve an extremely flat design and to assure a definite start in a particular direction, the stator winding is embodied with two coils, whose one coil side extends respectively over a group of stator yokes and yoke elements arranged in succession in the circumference direction, along the side of the yoke elements remote from the rotor shaft, between the yoke legs, where the group spanned by the coil side of the one coil is disposed spatially offset on the stator circumference and electrically offset by 90° in relation to the group spanned by the coil side of the other coil.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a 35 USC 371 application of PCT/DE 01/02668 filed onJul. 17, 2001.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention is directed to an improved unipolar transversal fluxmachine.

2. Description of the Prior Art

In a unipolar transverse flux machine of this kind (DE 100 21 914.4), ithas already been proposed to embody the stator winding as an annularcoil, which is disposed coaxial to the rotor axis and which, on theoutside of the yoke elements remote from the rotor axis, passes throughthe yoke legs of the stator yoke. As a result, the machine can beone-stranded, i.e. can be embodied with one stator module and one rotormodule, or can be multi-stranded, with at least two stator modules androtor modules, where each of the stator modules disposed axiallyadjacent to each other has an annular coil of this kind. In thetwo-strand design, the stator modules or rotor modules are disposedelectrically offset from each other by at least 90° and the annularcoils are supplied with current pulses in a bipolar fashion as afunction of the rotation angle of the rotor.

The single-strand machine with only one rotor module and stator modulehas the disadvantage that it cannot start by itself and additionalauxiliary measures must be provided for starting it. However, it has theadvantage of an extremely flat design.

SUMMARY OF THE INVENTION

The unipolar transverse flux machine according to the invention has theadvantage of an extremely flat design and a definite start in aparticular direction, which is assured by the two-strand design of thestator.

BRIEF DESCRIPTION OF THE DRAWINGS

An exemplary embodiment of the invention will be explained in detail inthe description that follows, taken with the drawings, in which:

FIG. 1 is a perspective depiction of a unipolar transversal flux motor,

FIG. 2 shows a section along the line II—II in FIG. 1, and

FIG. 3 shows a graph of the power supply to the stator of the motor.

DESCRIPTION OF THE EXEMPLARY EMBODIMENT

The unipolar transverse flux motor shown in various views and sectionsin the drawings as an exemplary embodiment of a universal unipolartransverse flux machine has a stator 11 and a rotor 12, which rotatesinside the stator 11 and is non-rotatably supported on a rotor shaft 13.

The rotor 12 is comprised of two coaxial ferromagnetic rotor rings 14,15 (FIG. 2), which are non-rotatably supported on the rotor shaft 13 andbetween themselves, clamp a permanent magnet ring 16, which ismagnetized in a unipolar fashion in the axial direction, i.e. in thedirection of the rotor axis or housing axis. In FIG. 2, the direction ofthe magnetization of the permanent magnet ring 16 is labeled N-S by wayof example. Each rotor ring 14, 15 is provided with a constant toothspacing on its outer circumference oriented away from the rotor shaft 13so that the teeth 18, which are separated from one another by respectivetooth spaces 17, of the tooth rows produced have a uniform rotationangle spacing from one another. The teeth 18 on the rotor ring 14 and onthe rotor ring 15 coincide with each other in the axial direction. Therotor rings 14, 15 with the teeth 18 formed onto them and of a piecewith them are laminate and are preferably comprised of uniform sheetmetal cutouts, which rest against one another in the axial direction.

The stator 11, which is disposed coaxial to the rotor 12, has U-shapedstator yokes 19 with two long yoke legs 191, 192, which are connected toeach other by a crosspiece 193, yoke elements 20, which are disposedbetween the stator yokes 19 and which in the exemplary embodiment areU-shaped, with two short legs 201, 202 that are connected to each otherby a crosspiece 203, and a stator winding 21. The stator yokes 19, whichconstitute the stator poles, and the yoke elements 20 are laminate andare composed of lamination bundles of stamped plates, where the widthb_(ZS) of the stator yokes 19 and the width of the yoke elements 20,each measured in the rotation direction, are approximately the same. Inthis connection, the ratio of the tooth with b_(ZR) of the teeth 18 onthe rotor rings 14, 15 to the tooth width b_(ZS) of the stator yokes 19and yoke elements 20 (each viewed in the rotation direction) is selectedto be greater than 1 and less than 2, preferably less than or equal to1.5. The stator yokes 19 are fixed to the housing 10 with a spacingwhich corresponds to the tooth spacing, and are disposed so that the oneyoke leg 191 is disposed opposite the one rotor ring 14 and the otheryoke leg 192 is disposed opposite the other rotor ring 15, each with aradial gap distance (FIG. 2). Between the stator yokes 19, there is arespective yoke element 20 disposed one half the yoke spacing apart fromthe stator yokes 19, where a certain offset is permissible in order, forexample, to reduce moment ripples. The yoke elements 20 are in turnoffset from each other by one yoke spacing. The yoke elements 20 extendover both rotor rings 14, 15 and are disposed with their short legs 201,202 opposite the rotor rings 14, 15, each with a gap distance. The gapdistance between the stator yokes 19 and the rotor rings 14, 15 on theone hand and the gap distance between the yoke elements 20 and the rotorrings 14, 15 on the other are the same size. The free end faces 194 ofthe yoke legs 191, 192 of the stator yokes 19 have at least the sameaxial width as the rotor rings 14, 15 or preferably protrude beyond thelatter on one or both sides. The same is true of the yoke elements 20,in which the free end faces 204 also have at least the same axial widthas the rotor rings 14, 15 or protrude beyond them on one or both sides.

The stator winding 21 is comprised of two identical coils 22, 23, inthis case kidney-shaped ones (FIG. 1), each with two coil sides 221, 222and 231, 232. The one coil side 221 or 231 of each coil 22 or 23 extendscoaxial to the rotor axis or the rotor shaft 13 and extends over a groupof stator yokes 19 and yoke elements 20 arranged in succession in thecircumference direction, where the coil side 221 or 231, on the side ofthe yoke elements 20 remote from the rotor shaft 13, extends throughbetween the yoke legs 191 and 192 of the stator yokes 19. Each group hasan equal number of stator yokes 19 and yoke elements 20 arranged insuccession in the circumference direction, which in the exemplaryembodiment totals six stator yokes 19 and six yoke elements 20. in thisconnection, the upper group spanned by the coil side 221 of the coil 22is disposed electrically offset by 90° at the circumference in relationto the lower group spanned by the coil side 231 of the coil 23, eachgroup containing a total of twelve stator yokes 19 and yoke elements 20.In FIG. 1, this is shown by the fact that the yoke elements 20 of thelower group spanned by the coil side 231 are radially aligned with theteeth 18 of the rotor 12, while the yoke elements 20 in the upper groupspanned by the coil side 221 are offset in the circumference directionfrom the teeth 18 of the rotor 12. With a tooth count of sixteen andtherefore a tooth division of 22.50°, the offset of the two groups ofstator yokes 19 and yoke elements 20 in relation to each other is 5.626°of circumference angle. The other coil side 222 or 232 of the coil 22 or23, on the outside of the stator yokes 19 remote from the rotor shaft13, extends over their crosspieces 193, likewise coaxial to the rotorshaft 13, and is shaped like a segment of a circle, the same as the coilsides 221 and 231.

In order to produce the electrical offset of 90° between the two groupsof stator yokes 19 and yoke elements 20 and to accommodate winding headsof the coils 22, 23, the number of stator yokes 19 belonging to a groupis less than the greatest possible number of stator yokes 19 based onthe tooth spacing or yoke spacing. In the exemplary embodiment of FIG.1, the rotor 12 has sixteen teeth 18. The maximal possible number ofstator yokes 19 is therefore likewise sixteen, as is the maximal numberof yoke elements 20. In the exemplary embodiment in FIG. 1, each coil22, 23, however, is only associated with six stator yokes 19 and sixyoke elements 20, which together yield a total of twelve poles for eachcoil 22, 23, where the coils 22, 23 are disposed with the respectivepoles diametrically opposite from one another in order to accommodatethe winding heads of the coils 22, 23 in the pole-free spaces.

The two coils 22, 23, which each represent a winding phase or a windingstrand of a two-phase, permanent magnet-excited motor, are supplied withcurrent pulses in a bipolar fashion as a function of the rotation angleof the rotor 12, where the current pulses in the coils 22, 23 arephase-shifted from each other by 90°, for example. The power supplypattern for the two coils 22, 23 is shown in FIG. 3 as a function of therotation angle θ of the rotor 12. The rotation angle distance betweeneach of the vertical lines shown is 5.625°.

The foregoing relates to preferred exemplary embodiments of theinvention, it being understood that other variants and embodimentsthereof are possible within the spirit and scope of the invention, thelatter being defined by the appended claims.

1. A unipolar transversal flux machine, in particular a unipolartransversal flux motor, comprising a rotor (12), which is non-rotatablysupported on a rotor shaft (13) and is comprised of two coaxialferromagnetic rotor rings (14, 15), which on their outer circumferenceremote from the rotor shaft (13), are provided with constant toothspacing, and having a permanent magnet ring (16), which is magnetized inan axially unipolar fashion and is clamped axially between the rotorrings (14, 15), and a stator (11), which is concentric to the rotorshaft (13) and has U-shaped stator yokes (19) with two yoke legs (191,192) that are connected to each other by a crosspiece (193), whichstator yokes (19) are fixed to a housing (10) with a spacing thatcorresponds to the tooth spacing, and are disposed so that the one yokeleg (191) is disposed opposite the one rotor ring (14) and the otheryoke leg (192) is disposed opposite the other rotor ring (15), each witha radial gap distance, yoke elements (20), each of which is disposedbetween respective stator yokes (19) arranged one after the other in therotation direction of the rotor (12), extends axially over the two rotorrings (14, 15), and is disposed opposite them with a radial gapdistance, and a stator winding (21), the stator winding (21) having twocoils (22, 23), each with two coil sides (221, 222 or 231, 232), whoseone coil side (221 or 231) extends coaxial to the rotor shaft (13),respectively over a group of stator yokes (19) and yoke elements (20)arranged in succession in the circumference direction, along the side ofthe yoke elements (20) remote from the rotor shaft (13), between theyoke legs (191, 192), and wherein the group spanned by the coil side(221) of the one coil (22) is disposed spatially offset on the statorcircumference and electrically offset by 90° in relation to the groupspanned by the coil side (231) of the other coil (23).
 2. The machineaccording to claim 1, wherein the other coil side (222 or 232) of thetwo coils (22, 23) extends on the outside of the crosspieces (193) ofthe stator yokes (19), remote from the rotor shaft (13).
 3. The machineaccording to claim 1, wherein each group has an equal number of statoryokes (19) and yoke elements (20) arranged in succession in thecircumference direction.
 4. The machine according to claim 2, whereineach group has an equal number of stator yokes (19) and yoke elements(20) arranged in succession in the circumference direction.
 5. Themachine according to 1, wherein the total number of stator yokes (19)spanned by the one coil sides (221, 231) of the two coils (22, 23) isless than the greatest possible number of stator yokes (19) based on thetooth spacing or yoke spacing.
 6. The machine according to 2, whereinthe total number of stator yokes (19) spanned by the one coil sides(221, 231) of the two coils (22, 23) is less than the greatest possiblenumber of stator yokes (19) based on the tooth spacing or yoke spacing.7. The machine according to 1, wherein the two coils (22, 23) aresupplied with current pulses in a bipolar fashion as a function of therotation angle (θ) of the rotor (12), and that the current pulses in thecoils (22, 23) are phase-shifted in relation to each other, inparticular by 90°.
 8. The machine according to 2, wherein the two coils(22, 23) are supplied with current pulses in a bipolar fashion as afunction of the rotation angle (θ) of the rotor (12), and that thecurrent pulses in the coils (22, 23) are phase-shifted in relation toeach other, in particular by 90°.
 9. The machine according to claim 1,wherein the stator yokes (19), the yoke elements (20), and the rotorrings (14, 15) are laminate.
 10. The machine according to claim 1,wherein the yoke elements (20) are disposed offset from the stator yokes(19), in particular by one half the yoke spacing.
 11. The machineaccording to claim 1, wherein the radial gap distance between the statoryokes (19) and the rotor rings (14, 15) on the one hand and the radialgap distance between the yoke elements (20) and the rotor rings (14, 15)on the other are the same size.
 12. The machine according to claim 1,wherein the the free end faces (194) of the yoke legs (191, 192) of thestator yokes (19) have at least the same axial width as the rotor rings(14, 15) and preferably protrude beyond the latter on one or both sides.13. The machine according to claim 1, wherein that width of the statoryokes (19) and the width of the yoke elements (20), each measured in therotation direction, are approximately the same.
 14. The machineaccording to claim 1, wherein the ratio of the tooth width (b_(ZR)) ofthe teeth (18) on the rotor rings (14, 15) to the width (b_(ZS)) of thestator yokes (19) and yoke elements (20), each viewed in the rotationdirection, is selected to be greater than 1 and less than 2, preferablyless than or equal to 1.5.
 15. The machine according to claim 1, whereinthat the yoke elements (20) are U-shaped, each with two short legs (201,202), which are disposed radially opposite a rotor ring (14, 15), and acrosspiece (203), which connects these legs to each other.
 16. Themachine according to claim 15, wherein the free end faces (204) of theshort legs (201, 202) of the yoke elements (20) have at least the sameaxial width as the rotor rings (14, 15) and preferably protrude beyondthem on one or both sides.